Power storage apparatuses are generally installed outdoors or in warehouses and basements, and are apt to waterlog when such an installation place floods. The waterlogging of the power storage apparatus may generate a short-circuit current, thereby causing electrocution. Therefore, it is necessary to ensure the safety of the power storage apparatus from waterlogging. For this, a circuit breaker is used to decrease the voltage of the power storage apparatus.
The circuit breaker interrupts an interconnection between cell modules included in the power storage apparatus or an interconnection between cells included in the cell modules, thereby decreasing a voltage detected through the power wires of the power storage apparatus to the voltage level of a cell module unit or cell unit.